Method of impressing and reading out a surface charge on a multi-layered detector structure

A method of recording and reading out a latent image comprising:

• placing a surface charge on the photoconductive layer of a multilayered detector apparatus;
• causing said surface charge to be distributed uniformly on said photoconductive layer;
• biasing said photoconductive layer with an electronic field whose polarity opposes said surface charge;
• discharing some portion of said surface charge of said photoconductive layer by exposing said detector to a modulated radiation flux capable of generating electron hole pairs in the photoconductor;
• scanning the surface of said partially discharged photoconductive layer with a small diameter photon beam whereby surface charge is sequentially further discharged;
• and
• measuring the changing electric potential of said sequential further discharge as a function of time.